Tuesday, October 11, 2016

Chapter 8

Chapter 8- Types of storage

-Storage holds data, instructions, and information for future use. A storage medium is the physical material on which a computer keeps data, instructions, and information.


-A storage device is the computer hardware that records and/or retrieves items to and from storage media.
-Reading is the process of transferring items from a storage medium into memory.
-Writing is the process of transferring items from memory to a storage medium.

Storage capacity:- 

-Access time is amount of time it takes a storage device to locate an item on a storage medium and time required to deliver an item from memory to the processor.
-A hard disk contains one or more inflexible, circular platters that use magnetic particles to store data, instructions, and information. Hard disks can store data using longitudinal recording or perpendicular recording.
-The characteristics of a hard disk include: -
  -Capacity
  -Platters
  -Cylinders
  -Access Time
  -Sectors and Tracks
  -Read/write Heads
  -Transfer rate
  -Revolutions per minute

-How a hard disk work: -

the hard disk arms move the read/write head,which reads items and writes item in the drive but location often is referred to by its cylinder. A head crash occcurs when a read/write head touches the surface of a platter and always keep a backup of you hard disk.

-Formatting is the process of dividing the disk into tracks and sectors so that the operating system can store and locate data and information on the disk.

-How disk cache works: -

-RAID (redundant array of independent disks) is a group of two or more integrated hard disks
-An external hard disk is a separate free-standing hard disk that connects to your computer with cable or wirelessly.
-A removable hard disk is a hard disk that you insert and remove from a drive.
-A network attached storage (NAS) device is a server connected to a network with the sole purpose of providing storage.

Flash memory storage: -
-Flash memory chips are a type of solid-state media and contain no moving parts
-Solid state drives (SSDs) have several advantages over magnetic hard disks
  -Faster access time
  -Faster transfer rates
  -Last longer
  -Generate less heat and consume less power

-A memory card is a removable flash memory device that you insert and remove from aa slot in a computer.
-USB flash drives plug into a USB port on a computer or mobile device.
-Cloud storage is an internet service that provides storage to computer users.
-An optical disc consists of a flat, round, portable disc made of metal, plastic, and lacquer that is written and read by a laser.
-Tape is a magnetically coated ribbon of plastic capable of storing large amounts of data and information where it read and writes data and information on a tape.
-A magnetic stripe card contains a magnetic stripe that stores information.
-A smart card stores data on a thin microprocessor embedded in the card.


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